2DPHOT: A Multi-Purpose Environment for the Two-Dimensional Analysis of Wide-Field Images

Barbera, F. La; Carvalho, R. R. de; Kohl-Moreira, J. L.; Gal, R. R.; Soares-Santos, M.; Capaccioli, M.; Santos, Rafael; Sant’Anna, N.

doi:10.1086/588614

Cited by 81 publications

(117 citation statements)

References 12 publications

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“…The sample galaxies are defined as bulge-dominated systems with passive spectra, while late-type systems are efficiently removed through the SDSS classification parameters based on the spectral type and the fraction of light that is better described by a de Vaucouleurs (1948) profile (see T+12 for further details). The structural parameters are measured using 2DPHOT (La Barbera et al 2008) and are found to be significantly different from the SDSS estimates (La Barbera et al 2010b). The sample is 95% complete at a stellar mass of M = 3 × 10 10 M , which corresponds to σ Ap ∼ 160 km s −1 .…”

Section: Data and Analysis Methodsmentioning

confidence: 90%

An Inventory of the Stellar Initial Mass Function in Early-Type Galaxies

Tortora

Romanowsky

Napolitano

2013

ApJ

105

158

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Given a flurry of recent claims for systematic variations in the stellar initial mass function (IMF), we carry out the first inventory of the observational evidence using different approaches. This includes literature results, as well as our own new findings from combined stellar population synthesis (SPS) and Jeans dynamical analyses of data on ∼4500 early-type galaxies (ETGs) from the SPIDER project. We focus on the mass-to-light ratio mismatch relative to the Milky Way IMF, δ IMF , correlated against the central stellar velocity dispersion, σ . We find a strong correlation between δ IMF and σ , for a wide set of dark matter (DM) model profiles. These results are robust if a uniform halo response to baryons is adopted across the sample. The overall normalization of δ IMF and the detailed DM profile are less certain, but the data are consistent with standard cold DM halos and a central DM fraction that is roughly constant with σ . For a variety of related studies in the literature, using SPS, dynamics, and gravitational lensing, similar results are found. Studies based solely on spectroscopic line diagnostics agree on a Salpeter-like IMF at high σ but differ at low σ . Overall, we find that multiple independent lines of evidence appear to be converging on a systematic variation in the IMF, such that high-σ ETGs have an excess of low-mass stars relative to spirals and low-σ ETGs. Robust verification of super-Salpeter IMFs in the highest-σ galaxies will require additional scrutiny of scatter and systematic uncertainties. The implications for the distribution of DM are still inconclusive.

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Section: Data and Analysis Methodsmentioning

confidence: 90%

An Inventory of the Stellar Initial Mass Function in Early-Type Galaxies

Tortora

Romanowsky

Napolitano

2013

ApJ

105

158

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“…We start from a sample of ∼ 0.4 million galaxies with high-S/N , measured photometry and structural parameters in all the four bands. For a subsample of these galaxies, we have used the KiDS photometry to estimate: 1) photometric redshifts based on machine learning techniques (Brescia et al 2014;Cavuoti et al 2015); 2) structural parameters using the software 2DPHOT (La Barbera et al 2008); 3) stellar masses, fitting colours with SPS model predictions. The resulting sample is > 90% complete down to an r-band magnitude ∼ 21, and down to a stellar mass of 3 − 5 × 10 10 M⊙, up to a redshift z ∼ 0.5.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, we have finally gathered those systems with the highest S/N in the r-band images, S/N r ≡ 1/MAGERR_AUTO_r> 50 (La Barbera et al 2008Barbera et al , 2010Roy et al 2016, in preparation). This sample consists of ∼ 380 000 galaxies.…”

Section: Kids High Signal-to-noise Galaxy Samplementioning

confidence: 99%

Towards a census of supercompact massive galaxies in the Kilo Degree Survey

Tortora¹,

Barbera²,

Napolitano³

et al. 2016

Mon. Not. R. Astron. Soc.

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The abundance of compact, massive, early-type galaxies (ETGs) provides important constraints to galaxy formation scenarios. Thanks to the area covered, depth, excellent spatial resolution and seeing, the ESO Public optical Kilo Degree Survey (KiDS), carried out with the VLT Survey Telescope (VST), offers a unique opportunity to conduct a complete census of the most compact galaxies in the Universe. This paper presents a first census of such systems from the first 156 square degrees of KiDS. Our analysis relies on g-, r-, and i-band effective radii (R e ), derived by fitting galaxy images with PSF-convolved Sérsic models, high-quality photometric redshifts, z phot , estimated from machine learning techniques, and stellar masses, M ⋆ , calculated from KiDS aperture photometry. After massiveness (M ⋆ > ∼ 8 × 10 10 M ⊙ ) and compactness (R e ∼ < 1.5 kpc in g-, r-and ı-bands) criteria are applied, a visual inspection of the candidates plus near-infrared photometry from VIKING-DR1 are used to refine our sample. The final catalog, to be spectroscopically confirmed, consists of 92 systems in the redshift range z ∼ 0.2 − 0.7. This sample, which we expect to increase by a factor of ten over the total survey area, represents the first attempt to select massive super-compact ETGs (MSCGs) in KiDS. We investigate the impact of redshift systematics in the selection, finding that this seems to be a major source of contamination in our sample. A preliminary analysis shows that MSCGs exhibit negative internal colour gradients, consistent with a passive evolution of these systems. We find that the number density of MSCGs is only mildly consistent with predictions from simulations at z > 0.2, while no such system is found at z < 0.2.

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“…The publicly available SPIDER sample includes 39993 passive galaxies selected from SDSS Data Release 6 (DR6), among them 5080 are in the near-infrared UKIRT Infrared Deep Sky Survey-Large Area Survey Data release (UKIDSS-LAS DR4) in the redshift range of 0.05 to 0.095. La Barbera et al (2010b) derived structural parameters in all available bands (grizY JHK) with single Sérsic fitting with 2DPhot (La Barbera et al 2008).…”

Section: Local Comparison Samplementioning

confidence: 99%

Sizes, colour gradients and resolved stellar mass distributions for the massive cluster galaxies in XMMUJ2235-2557 atz= 1.39

Chan

Beifiori

Mendel

et al. 2016

Mon. Not. R. Astron. Soc.

137

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(2016) 'Sizes, colour gradients and resolved stellar mass distributions for the massive cluster galaxies in XMMUJ2235-2557 at z = 1.39.', Monthly notices of the Royal Astronomical Society., 458 (3). pp. 3181-3209. Further information on publisher's website: Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTWe analyse the sizes, colour gradients, and resolved stellar mass distributions for 36 massive and passive galaxies in the cluster XMMUJ2235-2557 at z = 1.39 using optical and nearinfrared Hubble Space Telescope imaging. We derive light-weighted Sérsic fits in five HST bands (i 775 , z 850 ,Y 105 , J 125 , H 160 ), and find that the size decreases by ∼ 20% going from i 775 to H 160 band, consistent with recent studies. We then generate spatially resolved stellar mass maps using an empirical relationship between M * /L H 160 and (z 850 − H 160 ) and use these to derive mass-weighted Sérsic fits: the mass-weighted sizes are ∼ 41% smaller than their restframe r-band counterparts compared with an average of ∼ 12% at z ∼ 0. We attribute this evolution to the evolution in the M * /L H 160 and colour gradient. Indeed, as expected, the ratio of mass-weighted to light-weighted size is correlated with the M * /L gradient, but is also mildly correlated with the mass surface density and mass-weighted size. The colour gradients (∇ z−H ) are mostly negative, with a median value of ∼ 0.45 mag dex −1 , twice the local value. The evolution is caused by an evolution in age gradients along the semi-major axis (a), with ∇ age = d log(age)/d log(a) ∼ −0.33, while the survival of weaker colour gradients in old, local galaxies implies that metallicity gradients are also required, with ∇ Z = d log(Z)/d log(a) ∼ −0.2. This is consistent with recent observational evidence for the inside-out growth of passive galaxies at high redshift, and favours a gradual mass growth mechanism, such as minor mergers.

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2DPHOT: A Multi-Purpose Environment for the Two-Dimensional Analysis of Wide-Field Images

Cited by 81 publications

References 12 publications

An Inventory of the Stellar Initial Mass Function in Early-Type Galaxies

An Inventory of the Stellar Initial Mass Function in Early-Type Galaxies

Towards a census of supercompact massive galaxies in the Kilo Degree Survey

Sizes, colour gradients and resolved stellar mass distributions for the massive cluster galaxies in XMMUJ2235-2557 atz= 1.39

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